Hi OP- First of all, many best wishes to your dad. I'm a TVI, so most of my work is with kids with visual impairments, but I have learned a bit about adults as well, so take this with the appropriate grain of salt.
I would imagine he is probably chomping at the bit to do something that uses his brain.
$1 offers tuition-free courses for adults with VI/blindness - anything from braille to computers to cooking...all online. And the people are great. Check it out. =)
Second, I LOVE the suggestions so far about books!!! Totally! As far as some other leisure stuff, I might suggest swimming. It's gentle, relaxing exercise that's good for anyone in recovery of a major illness, and I know my legally blind/blind students especially love swimming because they say they "don't have to worry about running into anything" (aww).
Third...this is the one to DEFINITELY take with a grain of salt if you want...but depending on how independent he wants to be, you could go to a site like
$1 and get him a cane. Not for walking down any busy streets, not for traffic navigation, NOTHING like that. =) Just so that he can have a little help exploring the house, especially if it's on more than one level. That way he can do it himself, rather than making your mom do it, and you know how that all goes, so...
Finding little ways like that to allow independence in his own house is very important. If getting him a cheap cane can do that, it'll probably create less tension than having to have someone lead him everywhere.
If he has a bit of property around the house, you can twine trees - get a lot of really long twine, at about his waist level, and create a walking path for him. Wherever you want him to walk (keep it clear - no big branches in his way!) have that string running along the path, and he can follow it the entire route. You would just tie it to trees here and there and then continue the string until he returns to the house. It could be an independent way for him to go for a walk.
Last thing- you should do a sensory garden as a family. Edible flowers, vegetables, different types of mosses, rocks, clays, all of that could be so cool. Schools love those, so I'm sure googling it will come up with lots of ideas.
Good luck!